The capacity demands for communication networks is ever increasing. Various techniques have been devised for meeting these capacity demands. Optical networks can support large capacities. A single optical link, such as a fiber optic cable, may carry multiple data channels by using various diversity techniques, including for example wavelength division multiplexing (WDM) and/or polarization division multiplexing (PDM). The data carrying ability of each of the individual data channels may be increased using various data encoding or modulation techniques such as amplitude modulation, frequency modulation, and quadrature modulation.
Encoding, modulation and WDM/PDM techniques can provide increased capacity for optical links. However, additional techniques are required to meet the increasing capacity demands. One technique for increasing capacity of an optical link is space division multiplexing (SDM). SDM can be used to multiplex multiple optical signals, which in turn may be WDM and/or PDM signals, onto a signal optical link.
While SDM optical links allow the spatial multiplexing of multiple optical signals onto the single SDM optical link, the performance of the SDM optical links may limit their use.